1. Field of the Invention
The present invention relates to a coil element and a method for manufacturing thereof, particularly suitably used for an antenna incorporated in a small-sized communication device or a non-contact type smart IC card.
2. Description of the Prior Art
An antenna fitted to a working frequency band has been incorporated in a small-sized communication device or a non-contact type smart IC card such as a mobile telephone, a pager or a portable information-processing terminal equipment.
To realize a predetermined frequency characteristic, the conventional antenna may be formed on a printed circuit board by using a flat coil. In this regard, the coil is formed in a two-dimensional pattern, for example, of a spiral form or a zigzag form.
According to this prior art, since the coil is formed in a two-dimensional manner on the printed circuit board, it is difficult to realize a high inductance if a pattern size is minimized, resulting in a problem in that a working frequency band is liable to be limited.
An object of the present invention is to solve the above-mentioned drawbacks of the prior art by providing a three-dimensional coil element capable of realizing a high inductance even though a pattern size is small and a method for manufacturing thereof.
A first aspect of the present invention is a coil element comprising: a plurality of first conductive materials formed on a base material at a predetermined pitch; an insulation material formed on the base material to cover the first conductive materials except for opposite ends of the first conductive materials; and a plurality of second conductive materials formed on the insulation material at a predetermined pitch to be alternately conductive to the opposite ends of the first conductive materials; wherein the first conductive materials and the second conductive materials are alternately connected to each other while interposing the insulation material between the both, to form a three-dimensional coil.
According to the first aspect of the present invention, the three-dimensional coil is formed, wherein the first conductive materials are alternately connected to the second conductive materials on the base material while interposing the insulation material between the both. By properly adjusting the pitch, width, or length of the coil, it is possible to obtain a markedly dense winding of the coil in comparison with that obtained from a coil of a two-dimensional flat pattern, whereby an antenna is realized, has a high sensitivity which is excellent in a transmission distance and has a higher inductance even though a pattern size is smaller.
In the coil element of the first aspect of the present invention, when the insulation material forming a core of the coil is made of magnetic material and preferably multi-layered, it is possible to increase the coil inductance.
A connection terminal is preferably added to one end of the coil for facilitating the connection of the coil to an external electric circuit.
In order to mechanically protect the second conductive materials, to prevent the coil from being broken, or to avoid the second conductive materials from being oxidized, a protective material may be provided on the base material to cover the second conductive materials.
A plurality of coils may be superposed on the base material as coil layers. For example, a plurality of coils having different resonant frequencies may be superposed on each other in the same orientation to form an antenna element of a stacked type having a broad frequency band characteristic, or a plurality of coils may be superposed on each other in the different orientations to form a so-called polarized wave synthetic array type antenna element capable of transmitting and/or receiving both of horizontally and vertically polarized waves.
A second aspect of the present invention is a method for manufacturing a coil element comprising the steps of: printing a plurality of first conductive materials on a base material; providing an insulation material on the base material to cover the first conductive materials except for opposite ends of the first conductive materials; and printing a plurality of second conductive materials on the insulation material at a predetermined pitch to be alternately conductive to the opposite ends of the first conductive materials; wherein the first conductive materials and the second conductive materials are alternately connected to each other while interposing the insulation material between the both, to form a three-dimensional coil.
According to the second aspect of the present invention, it is possible to easily form a three-dimensional coil solely by a printing process even though the base material is a thin flexible film or the like.
A third aspect of the present invention is a method for manufacturing a coil element comprising the steps of: forming a plurality of first conductive materials on a base material at a predetermined pitch by etching a conductive layer preliminarily provided on the base material; providing an insulation material on the base material to cover the first conductive materials except for opposite ends of the first conductive materials; and printing a plurality of second conductive materials on the insulation material at a predetermined pitch to be alternately conductive to the opposite ends of the first conductive materials; wherein the first conductive materials and the second conductive materials are alternately connected to each other while interposing the insulation material between the both, to form a three-dimensional coil.
According to the third aspect of the present invention, since a printed circuit board may be used as the base material, it is possible to simultaneously form necessary leads and/or connection terminals together with the first conductive materials.
In the second and third aspects of the present invention, a step may be added for providing a protective material on the base material to cover the second conductive materials.
According to the present invention, since the coil is formed by printing or etching the first conductive materials on the base material and then sequentially superposing the insulation material and the second conductive materials thereon, it is possible to extremely easily manufacture the coil element.
The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.